Polyketone polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles, such as containers for food and beverages and parts for the automotive industry, which are produced by processing the polyketone polymer according to well known methods. For some particular applications, it is desirable to have properties which are somewhat different from those of the polyketone polymers. The more desirable properties of the polyketone polymers may be retained, and yet other properties improved, through the provision of a polymer blend. Blending one polymer with a less expensive polymer provides a less expensive polymer product, in addition to properties appropriate for various applications.
Polypropylene polymer, for example, is a relatively inexpensive polyolefin polymer with a good balance of properties, making it one of the top three plastics in the world on a volume production basis. However, the non-polar nature of polypropylene makes it difficult to blend with the polar polyketone polymers without the occurrence of gross phase separation.
It has been found that polypropylene polymers that have been cracked or degraded by contact with peroxides can be blended with polyketone polymers, without experiencing phase separation. The cracking process apparently introduces oxygen-containing groups into the polypropylene polymer chain, making it more compatible with the polar polyketone polymers. Blends of polyketone polymers which contain cracked polypropylene are expected to be particularly useful in packaging applications due to the superior water barrier properties exhibited by polypropylene.
It is an object of this invention to provide a blend of a polyketone polymer and a cracked polyolefin polymer.